CONFIG_DEBUG_LL is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Kernel low-level debugging functions (read help!)

modulename: debug.ko

configname: CONFIG_DEBUG_LL

Linux Kernel Configuration
└─>Kernel low-level debugging functions (read help!)
In linux kernel since version 2.6.12  
Say Y here to include definitions of printascii, printch, printhex
in the kernel. This is helpful if you are debugging code that
executes before the console is initialized.

Note that selecting this option will limit the kernel to a single
UART definition, as specified below. Attempting to boot the kernel
image on a different platform *will not work*, so this option should
not be enabled for kernels that are intended to be portable.

source code: